am 522ab34d: AI 149272: Mark 1.5r1 as a "non-current" release, with pointer to 1.5r2.   BUG=1790234

Merge commit '522ab34d3821dc760e10f4bdf3fbdb558c6a1d01' into donut

* commit '522ab34d3821dc760e10f4bdf3fbdb558c6a1d01':
  AI 149272: Mark 1.5r1 as a "non-current" release, with pointer to 1.5r2.